Protective device



- April 1944- E. w. DRESCHER PROTECTIVE DEVICE Filed Nov. 14, 1941 INVENTOR. ERNEST W. DRESCHER ATTORNEYS.

Patented Apr. 11, 1944 UNITED STATES PATENT OFFICE 2,346,476 PROTECTIVE DEVICE Ernest William Dreseher, Manheim Township, Lancaster County, Pa., assignor to Hamilton Watch Company, Lancaster, Pa.

Application November 14, 1941, Serial No. 419,145

2 Claims.

This invention relates to protective devices for timepieces and has particular reference to improved means and method of protecting a timepiece from dust and moisture.

An object of this invention is to provide improved means and method of preventing dust and moisture from entering a timepiece about the stem thereof.

Another object is to provide an improved dust and moisture seal for a timepiece stem, which is adapted to operate efficiently with the stem in either winding or setting position.

Another object is to provide a stem unit as described, which may very readily be disassembled.

Another object is to provide a stem unit as described, in which an efiicient dust and moisture seal may be maintained even upon the removal of the crown.

Another object is to provide a protective unit as described, including a sleeve with its bore having a relatively long section in such snug fitting sliding relation with a shaft, and under such resilient pressure along said shaft in the direction of a cap member, as to strongly resist the passage of dust and moisture to the timepiece.

Another object is to provide a dust and moisture seal for a. timepiece stem assembly with substantial clearances for the fitting of the stem in the watch case.

Other and further objects will be clearly apparent from the following specifications and from the drawing.

Referring to the drawing:

Fig. I i an elevation of the device embodying this invention, in partial vertical central section;

Fig. II is an illustration of an alternate structure, showing the central portion of Fig. I in difierent arrangement; and

Fig. III is a plan view of the structure of Fig. I with crown 6 and bow 3 removed.

This invention is directed to dust and moisture sealing in connection with timepiece stem Another important feamoisture out of the timepiece but also provides desirably substantial clearances in the fit of the stem within the stem opening of the timepiece case.

As illustrated in the drawing the device embodying this invention is mounted on the timepiece housing or watch case I, of which only a portion sufiicient to illustrate the invention is shown. Secured to the case I is a support 2 for a bow 3.

The case I has an opening 4 through which a stem 5 extends, and a crown 6 is threaded on the upper end of the stem 5.

The bow support 2 is provided with an upstanding hollow central hub 1 which is internally The cap 8 is provided with Fig. II, in its top face, so that a screw driver or similar tool may be used to thread the cap 8 in or out of the hub 7.

A sleeve II is mounted on the stem 5 in snug fitting sliding relation therewith and it is a feature of this invention that while the stem 5 is slidabl in the sleeve II, it has such a snug fit therewith as to strongly resist the passage of dust or moisture. With this arrangement, for example, the stem may be pulled out into the setting a watch. The sleeve horizontal slots l0,

watch case by passing between the stem 5 and the sleeve II is very The dimensions of the openings 9 8, 12 of the hub 1 sleeve I I, with substantial assembly clearances.

It is important, from a practical standpoint in the manufacture would make such an arrangement normally undesirable.

This invention provides such desirable clearances and a dust and moisture proofing arrangement which effectively seals the openings formed 2 thereby. This is illustrated in Fig. I, and it will be seen that there is room to vary the location of the stem with its associated sleeve H and crown 6, within the diametric confines of the openings 4, l2, and 9.

In order to prevent dust entering the case between the sleeve H and the wall of the opening 4, the sleeve H is provided with a flange I3 on its upper end, and this flange is resiliently pressed against the bottom of the cap 8, in surface to surface relation therewith. This resilient pressure is accomplished by means of a spring l4, surrounding the sleeve I I, with its upper end bearing against the under side of the fiange l3, and its lower end bearing on a washer 15 which fits snugly about the sleeve H, and rests on the case I so as to cover that part of the opening l which remains after the insertion ofthe stem 5 and sleeve ll.

Consequently, in order to enter the case between the wall of the opening 4 and the sleeve H, dust must first pass between the top surface of the fiange t3 and the bottom surface of the cap 8, which are held together by resilient pressure. Even if the dust did get by these spring pressed surfaces it would still have to pass eitherbetween the sleeve H and its snug tt-ing washer l5, or between the spring pressed surfaces of the washer l5 and the case i.

In addition to the above described barriers, a tortuous passage is provided, through which the dust must-pass before it gets to the traps.

The crown 6 is soformed as to surround the hub i andto extend well below the upper surface thereof. Consequently dust, to reach the traps described, must first travel beneath the hub surroundingportion of the crown 6, up the outside, across the top, and down the inside of the hub'l. Even with the-crown 6 removed, dust or moisture stillhave barriers to theirentrance to the watchcase.

It is pointed out that the arrangement of this deviceis such as to facilitate assembly and disassembly andthat the crown without release of the spring pressure, or diminishing the effectiveness of the major dust and moisture barriers, and the-stem 5'may bepulled out tosetting position by sliding through in anyway diminishing thesleeve H, withouteffectiveness of:the dust and moisture resistance of these barriers.

The arrangement of: this invention provides considerable resistance to into the case, and-when, as isdesirable, lubrication is placed between-the. cap 8 and flange l3 and between the stem Saandsleeve II, the resistance to-the passage of dust andmoisture, is, for all practical: purposes, essentiallyv com- 6 i may be removedtheentry of moisture:

plete. A further step to aid in dust and moisture proofing is the filling of the opening l2 in the hub 1, with heavy grease of the type which resists fluidity, or other suitable packing.

An alternate construction is illustrated in Fig. II. This arrangement is designated particularly to increase the protection against moisture, and consists of a packing, ring it, surrounding the stem 5 in snug fitting relation therewith and held between the lower face of the cap 3 and the upper end of the sleeve H by the spring 14. The packing ring l6 and the upper end of the sleeve H are both out at such an angle, as at H, that the packing is forced, by the spring l4, both against the cap 8 and against the stem. 5.

The unthreaded portion of stem 5 in this arrangement extends upward at least beyond the bottom of the cap 8, and the central threaded hub of the crown 6 is modified to allow for this extension.

What I claim' is 1. A dust cap for watches comprising a watch case having an opening therein, a pend-ant block formed with asegment of an annular recessand securedtosaid case andhaving a threaded opening aligned with said watch caseopening; a sleeve having an upper shoulder passingthrough said case opening, a sealing washeraround' said sleeve and seating against the case within the threaded opening,. a coil" spring, about. said sleeve and resiliently urgingsaid annular shoulder and said washer apart, ascrew plugthread'edii'n said pendant block opening and bearing on saidisleeve shoulder, a stem. slidable in said. sleeve and a crown on. said stem, said, crown being. formed with. a. downwardly projecting rim. fitting, into the recess of said pendant block.

2. A dust cap for watches comprising awatch case, having. an opening therein, a-.pendant block.

secured to said case andhaving a threadedopening aligned with said; watch. case opening, a

Watch-stem passing throughsaid caseopening.

and said. pendant.w opening, a, sleeve slidably mounted; on said watch stem and formed with an annular shoulder at its upper end, a washer; mounted on, said sleeve andclosing said case opening, ascrew plug threaded in said pendant:

block opening andbearing against. said-sleeve and a coil spring bearing against saidannular shoulder and,said.washer providing dust proof connection .at said case. opening, the; threaded. plug bearing against the upper part of the :sleeve:

serving to adjust the tensionof said coil-spring, and a crown ongsaid watch stem. 7 ERNEST. WILLIAM DRESCHER. 

